1. Technical Field of the Invention
The present invention is directed to Distributed Antenna Systems (DASs) and more particularly, to methods and systems for real time control of an active antenna over a DAS.
Distributed Antenna Systems are used to provide or enhance coverage for wireless services such as Public Safety, Cellular Telephony, Wireless LAN and Medical Telemetry inside buildings and over campuses. The general architecture of a DAS is depicted in FIG. 1.
A single DAS can serve a single wireless service (WS) or a combination of many wireless services operating over multiple bands. With respect to medical telemetry services, a medical telemetry system (MTS) access point can be connected to the DAS through the remote wiring closet and using a wireless medical telemetry system (WMTS) module and a service combiner module, the WMTS system can be supported by the DAS using one or more passive antennae.
One desired characteristic of a multi-service DAS is that it can use a single antenna to radiate and receive the signals for all services and frequency bands supported by the DAS. Such an antenna would need to cover (i.e. have acceptable performance) in all frequency bands of interest and is commonly referred to as a Broadband Antenna. An example of a supported frequency range for a DAS antenna would be 400 MHz-6 GHz. To provide MIMO based services, a MIMO antenna which includes multiple antenna elements at a common location can be used.
In referring to the signal flows in DAS systems, the term downlink signal refers to the signal being transmitted by the source transmitter (e.g. cellular base station) through an antenna to the terminals and the term uplink signal refers to the signals being transmitted by the terminals which are received by an antenna and flow to the source receiver. Many wireless services have both an uplink and a downlink, but some have only a downlink (e.g. a mobile video broadcast service) or only an uplink (e.g. certain types of medical telemetry).
2. Description of the Prior Art
A conventional WMTS includes an access point which is connected to the supporting network by a wired connection such as an Ethernet or other LAN connection. The access point typically includes up to 4 radio frequency (RF) connections and at least one control and power connection. Each of the RF connections can be connected directly to an antenna or to a remotely located active antenna unit. Where the access point is connected to one or more remotely located active antenna units, a control and power connection is used to provide power and control signals to the remotely located active antenna. In some embodiments, antenna diversity can be provided to improve quality and reliability of the wireless link by providing two or more separate antenna elements at each antenna unit for a given WMTS link.